Dilators are known devices for creating surgical access sites. Once an operative level is identified and an incision is created, dilators are used to create a surgical access site which is often followed by the use of a retractor or other specialized tools to create a surgical access corridor.
When accessing certain areas of a patient, it is desirable to avoid neural elements or nerves. For example, during a lateral approach to a patient's spine, a psoas muscle, which is located on either side of the spine, is separated in order to access the spine and, in particular, an intervertebral disc space or one or more vertebral bodies within a patient's spinal column. It is desirable to avoid neural elements or nerves of the lumbar plexus that lie within the psoas muscle during such procedures. The anterior third of the psoas muscle is typically considered a safe zone for muscle separation.
The neural elements or nerves of the psoas muscle may be mapped using a probe. In this manner, the most posterior neural or nerve free area of the psoas muscle may be located and identified. The probe may then be inserted through the psoas muscle via the most posterior neural or nerve free tissue area or through nearly any other region that is free of neural elements or nerves and toward the spine or into the intervertebral disc space in order to initiate safe tissue separation of the psoas muscle. Dilators are next placed over the probe to create and enlarge a surgical access site. Following the use of dilators, a retractor or other specialized tools are used to further enlarge the surgical access corridor.